Direct digital synthesis is a method of producing an analog waveform—usually a sine wave—by generating a time-varying signal in digital form and then performing a digital-to-analog conversion. Because operations within a DDS device may be primarily digital, such a device may offer fast switching between output frequencies, fine frequency resolution, and operation over a broad spectrum of frequencies. With advances in design and process technology, today's DDS devices may be very compact and may draw little power.
In some cases, a DDS may be used to digitally generate signals for transmission to a circuit-under-test. These synthesizers may be configured to receive digital data words from a source device and to convert these digital signals to analog signals for transmission to the circuit-under-test.
Unfortunately, the analog output waveform generated by the DDS may have spurious frequency components produced by non-linearities in the DDS. Traditional low-distortion sinusoidal generators require complex filtering techniques to remove all of these spurious components.